GEO Status and Prospects Harald Lück ILIAS / ETmeeting Cascina November 2008

2 GEO600 still in Astrowatch Allways observing but only doing triggered searches

GEO600 Sensitivity Evolution

Astrowatch science time 4 Nov June Nov Total 12 months:86.3%

5Plans  Until Spring 2009: Astrowatch + low-risk commissioning until Enhanced IFOs come online  After Spring 2009: Upgrade GEO600 towards GEO HF  Keywords: DC readout, squeezing, tuned SR, lower SR factor, OMC, higher power, thermal comp., extend digital control...

Now:   Auto Alignment on detection bench   Main photo detector on detection bench outside vacuum system Then: Auto Alignment on new AA bench Main photo detector in additional vacuum tank OMC to reduce higher order TEM mode contributions to detected light

GEO HF layout Output section Inject squeezed light to lower shot noise

Going to tuned DC (Achieved during Astrowatch time and without OMC) Future work On AA Same sensitivity Higher shot noise (future work, OMC) Tuned homodyne 550Hz heterodyne Two major changes in the GEO configuration Signal recycling tuned to 0 Hz Switch from heterodyne to homodyne

Tuned DC noise budget Prelimirary noise budget Very promising Need to AA noise and oscillator noise More gain expected with OMC Dark noise will be reduced with the new HPD Much lower Roughly same level as for heterodyne detuned

New GEO output in 2009 For tuned DC -> Redesign of GEO output insert new vacuum tank add a Faraday rotator add OMC HPD now in vacuum

Details of the OMC Purpose: reject sidebands reject higher order modes Design: 4 mirrors ring cavity finesse: 150 g factor: round trip length: 66cm all made in fused silica Glueing all the optics: Jan 09 Testing in AEI: Feb 09 Installing and commissioning: Spring 09

Currently MPR Increase laser power 10 W (6 W) -> 35 W Exchange MC mirrors -> increase throughput 2x -> MPR Power increase

Thermal lensing compensation 3 kW Temperature distribution in the beam splitter CO2 heating pattern Different from other GW detectors: thermal lensing compensation for the BS: Low power absorbed (< 10mW)... But 10 × more later Required asymetric heating pattern for compensation

Thermal lensing compensation Example 2 kW circulating in the BS, optical path simulation Also investigating TCS with radiative element Without compensationWith compensation (1.2W) Scattering loss reduced by a factor 5

New digital control system System already used by LIGO Real time Linux with EPICS user interface ADC/DAC and I/O digital 64 kHz Data directly saved in Frame Format Commissioning started in August administrators working on it and already 6 users trained.

16 Mirror Modes MFN MCE MCNMFE ~3e-18 m/rt(Hz)‏

17 Mirror Modes

18 Cool Mirror Modes MFN MCE MCN

19 Optically Cooled Mirror Modes MFN MCE MCN Highest mode suppression factor : ~250 Factor in Power -> T eff ca. 5mK Mirror mass: 5.6 kg From June 2008

Timeline / Summary  DC readout  OMC  In vacuum read out  Test new locking script  Test new digital control system  Squeezed light into output port comissioning new AA  Increase laser power  Exchange MC mirrors > Spring